Variable condenser



Nov. 19, 1929. 1 'r. B. BLbu H ET AL 1,735,889

VARIABLE cdNDENsER Filed March 5, 192'? INSULATION I IIINSULATIDN I INVENTOR Patented Nov. 19', 1929 UNITED STATES PATENT OFFICE JQHN T. B. BLOUGH, 0F EAST]. PITTSBURGH, AND CHRONIS'IER, OF "TURTLE CREEK, PENNSYLVANIA VARIABLE CONDENSER Application filed March 5, 1927. Serial No. 172,986. a

This invention relates to electrical condensers, more particularly to variable condensers especially applicable for use in radio frequency receiving systems.

i It is among the objects of the invention to provide a variable condenser which'shall provide minute adjustment of the air gapbe-' tween the conductor elements to vary the di-- provide a variable condenser of the above designated character which shall be of simple and compact mechanical construction and which shall be relatively inexpensive to manufacture in production quantities.

Variable condensers as heretofore constructed comprise a plurality of substantially segment-shaped plates or conductor elements rigidly secured in spaced-apart relation having a series of plates of equal area interposed and mountedfor movement between the fixed plates. The movable elements are secured to a common shaft which is rotatable to provide adjustment of the movable plates with the fixed plates. In this construction the air gap between the plates is co? tant.

In accordance with the present invention a pair of corrugated conductor elements of tubular form are disposed one within the other and mounted to provide relative movement axially and angular-1y to -vary the capacity of the condenser.

In the accompanying drawing constituting a part hereof and in which-like referencecharacters designate like parts, Figure 1 is a diagrammatic view in side elevation of a variable condenser embodying the principle of this invention, and Figure 2 a cross-sectional view thereof taken along the line IIII, Figure 1. 1

As shown inFig. 2 the structure comprises a pair of conductor elements 1 and 2 of tubu-' lar shape, and provided with corrugations 3 and 4, respectively. The member 2 is movably mounted on a short stud shaft 5, Fig. 1, which is secured in a'pedestal 6. The shaft 5 is provided with a shoulder or flange 7 against which the end wall of the member 2*is yieldingly held by a coil spring 8 which is retained by a screw and washer 9 and 10,

respectively.

Them-ember 1 is similarly mounted on a shaft 11 against a shoulder 7 on which it is mounted by spring 8, screw 9 and washer 10. The shaft 11 is axially movable in a pedestal 6 and also angularly movable therein. The pedestals 6 and 6' are secured in suitable spaced relation to a base 12. End of shaft 11 is provided with a constricted .portion 18 for receiving a knob, (not shown).

Pedestals 6 and 6 and the shafts 5 and 11 are of all metal construction and the base '12 consists of suitable insulating material. Screws l4=and 15 are provided to constitute the terminal posts of the condenser.

The operation of this device is briefly as follows: The member 1 may be moved axially on its supporting shaft 11 to envelop the member 2. The amount of overlapping of the members 1 and 2 determines theeffective surfaces of the conductors, and adjustment sol of these members changes the capacity of the condenser. Angular movement of the shaft.

structed and that they are relatively simple and inexpensive to manufacture. I claim:

' 1'. A variable condenser comprising a pair of corrugated conductor elements of substantially cylindrical form, insulated from each other and disposed one within the other and having their respective corrugations interacting, terminals for electrically connecting said elements and means for efiecting relative axial and angular movement of said elements.

2. A variable condenser comprising a pair of corrugated conductor elements of substantially cylindrical form, insulated from each other and disposed one within the other,

said elements having' an air gap therebe= tween, oneof said elements beingfl'mounted' ona fiX edsupport and the other on a movable support the latter being adapted for axial and angular movement, and terminals for connecting said conductor elements in ail-electrical circuit.

3. A variable condenser comprising a pair of corrugated conductor elements of substanti ally cylindrical form insulated from each other and having their corrugations radially disposed, terminal posts for connecting Lev/1 5 said elements in an electrical circuit, and

means adapting said conductor elements for relative axial and angular movement.

In testimony whereof, We hereunto sign "our names.

JOHN TQB. BLOUGH.

ELMER-E. CHRONISTER. 

